Giant magnetoimpedance and domain structure in FeCuNbSiB films and sandwiched films

Longitudinal and transverse giant magnetoimpedance (GMI) effects are studie d in FeCuNbSiB and FeCuNbSiB/Cu/FeCuNbSiB films. In regard to as-deposited single layer films, hardly any GMI effect can be detected, while for as-dep osited sandwiched films, the maximum GMI ratios of 32% and 11% are obtained in longitudinal and transverse fields, respectively. After annealing, the maximum GMI ratios of 18% and 14% are obtained for the single-layer films i n longitudinal and transverse cases, while for the sandwiched films, the ma ximum GMI ratios are 67% and 80% in longitudinal and transverse cases, resp ectively. A giant magneto-inductance ratio as large as 1733% is obtained in annealed sandwiched films at a low frequency of 100 kHz. In order to know the relation between GMI effect and magnetic properties of the samples, the domain structures are observed by the Kerr effect.